1. Feature Of The Week: Growth Kinetics of Concave Nanocubes Studied by Optical Coherence Tomography

    This work presents the analysis of the growth kinetics of two syntheses of concave gold nanocubes with a mean size of 72 and 108 nm followed by the optical coherence tomography (OCT) technique by acquiring B-scan images each 5 s. In addition, ultra violet-visible (UV-Vis) spectra and mean size from dynamic light scattering (DLS) were acquired during nanoparticle growth to generate kinetic plots in order to corroborate the OCT results. Kinetic plots from OCT images were obtained by plotting contrast enhancement of B-scan images as function of time. Fitting parameters values given by using the classical Kolmogorov-Johnson-Mehl-Avrami (KJMA) equation show that the growth rate parameter k is higher for small cubes than for large ones, and that the Avrami exponent n associated to the growth kinetics of concave nanocubes is close to 2 for both syntheses. The results of UV-Vis spectroscopy and DLS confirm that OCT is a viable technique to provide information about nanoparticle growth kinetics. Moreover, to our knowledge, this is the first time that OCT technique is used to follow nanoparticle growth kinetics.

    For more information see recent Article. Courtesy Yenisey Ponce de León from the Centro de Investigaciones en Óptica, A.C. To share this article click Here.
  2. Recent Articles From Around The Web

    1. Towards Extreme Ultra Violet Coherence Tomography with High Harmonic Generation Light Sources

      Towards Extreme Ultra Violet Coherence Tomography with High Harmonic Generation Light Sources

      Optical coherence tomography (OCT) is a well-established method to retrieve three-dimensional, cross-sectional images of biological samples in a non-invasive way using near-infrared radiation. The axial resolution of OCT is on the order of the coherence length lc / 20 =FWHM which depends on the central wavelength 0 and the spectral width (FWHM) FWHM of a light source. As a consequence, the axial resolution only depends on the spectrum rather than the geometrical properties of the radiation. OCT with broadband visible and near-infrared sources typically reaches axial (depth) resolutions in the order of a few micrometers [1]. However, in contrast, extreme ultra ...

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    2. Reproducibility of In-Vivo OCT Measured Three-Dimensional Human Lamina Cribrosa Microarchitecture

      Reproducibility of In-Vivo OCT Measured Three-Dimensional Human Lamina Cribrosa Microarchitecture

      Purpose To determine the reproducibility of automated segmentation of the three-dimensional (3D) lamina cribrosa (LC) microarchitecture scanned in-vivo using optical coherence tomography (OCT). Methods Thirty-nine eyes (8 healthy, 19 glaucoma suspects and 12 glaucoma) from 49 subjects were scanned twice using swept-source (SS−) OCT in a 3.5×3.5×3.64 mm (400×400×896 pixels) volume centered on the optic nerve head, with the focus readjusted after each scan. The LC was automatically segmented and analyzed for microarchitectural parameters, including pore diameter, pore diameter standard deviation (SD), pore aspect ratio, pore area, beam thickness, beam thickness SD, and ...

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    3. Expectations and limitations of contemporary intravascular imaging: lessons learned from pathology

      Expectations and limitations of contemporary intravascular imaging: lessons learned from pathology

      Acute coronary syndrome is the leading cause of death worldwide and plaque rupture is the most common underlying mechanism of coronary thrombosis. During the last 2 decades the understanding of atherosclerotic plaque progression advanced dramatically and pathology studies provided fundamental insights of underlying plaque morphology, which paved the way for invasive imaging modalities, which bring a new area of atherosclerotic plaque characterization in vivo. The development of intravascular ultrasound (IVUS) allowed the field to evaluate the principles of vascular anatomy, which is often underestimated by coronary angiography. Furthermore, IVUS image technologies were developed to obtain improved characterization of plaque composition ...

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    4. Orthogonal dispersive spectral-domain optical coherence tomography

      Orthogonal dispersive spectral-domain optical coherence tomography

      Ultrahigh depth range spectral domain optical coherence tomography (SDOCT) can be realized based on the orthogonal dispersive spectrometer consisted by a high spectral resolution virtually-imaged phased array (VIPA) and a low spectral resolution grating. However, two critical issues result in the challenge of obtaining desirable one-dimensional (1-D) spectra from the recorded two-dimensional (2-D) orthogonal spectra for high-quality OD-SDOCT imaging. One is the wavenumber mapping errors and the other is the periodic intensity modulations. The paper proposes a method for desirable reconstruction of 1-D spectra from the recorded 2-D orthogonal spectra. A sample etalon with identical parameters to the dispersive VIPA ...

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    5. Simultaneously measuring the refractive index and thickness of an optical sample by using improved fiber-based optical coherence tomography

      Simultaneously measuring the refractive index and thickness of an optical sample by using improved fiber-based optical coherence tomography

      An improved structure for the optical coherence tomography (OCT) scheme based on a 4 × 4 fiber coupler for simultaneously measuring the refractive index and thickness of optical samples is presented. The proposed structure incorporates the optical path length difference of interference light and is used to calculate the refractive index and thickness of an unknown sample without any prior knowledge of the sample parameters. Two methods (time-domain and Fourier-domain OCT) of obtaining information about an unknown sample are proposed, and a high-speed high-resolution OCT system was developed.

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      Mentions: Hsu-Chih Cheng
    6. Optical Coherence Tomography-guided Bifurcation Stenting of a Coronary Artery Dissection

      Optical Coherence Tomography-guided Bifurcation Stenting of a Coronary Artery Dissection

      Periprocedural guide-wire induced coronary artery dissection is a rare but potentially serious complication of PCI. Immediate stenting of the entry point is one of the therapeutic options but engaging the guide-wire in the true lumen may be challenging. We report a case of a 55-year-old woman with a guide-wire induced coronary dissection that occurred during treatment of a bifurcation lesion. Optical coherence tomography was instrumental to distinguish true form false lumen and thereby guide correct positioning of the guide-wire to successfully treat the lesion using a dedicated bifurcation stent.

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    7. Preservation of the Photoreceptor Layer following Subthreshold Laser Treatment for Diabetic Macular Edema as Demonstrated by SD-OCT

      Preservation of the Photoreceptor Layer following Subthreshold Laser Treatment for Diabetic Macular Edema as Demonstrated by SD-OCT

      Purpose: Subthreshold laser treatment of diabetic macular edema (DME) may have less deleterious effects on the photoreceptors than regular continuous wave laser. This study aimed to assess whether subthreshold laser causes a long-term damage to the retinal structures, as demonstrated by spectral-domain optical coherence tomography (SD-OCT), and to evaluate the change in the axial diameter of retinal diabetic microaneurysms following treatment. Methods: A retrospective study of eyes that were diagnosed with non-foveal involving DME and underwent subthreshold laser treatment with the Lumenis Novus SRT system. SD-OCT scans of treated retinal areas, performed prior to treatment and approximately 4 months following ...

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    8. Hyperreflective Pyramidal Structures on Optical Coherence Tomography in Geographic Atrophy Areas

      Hyperreflective Pyramidal Structures on Optical Coherence Tomography in Geographic Atrophy Areas

      Purpose: We observed hyperreflective dome-shaped or pyramidal structures (HPS) on spectral domain optical coherence tomography (SD-OCT) in patients affected with geographic atrophy (GA). Our purpose was to describe the multimodal imaging features of HPS identified in areas of GA in patients with age-related macular degeneration. Methods: This is a retrospective case series of patients with GA harboring HPS in atrophic areas. Multimodal imaging examination including infrared reflectance, fundus autofluorescence, and SD-OCT, was performed for each patient. Infrared and fundus autofluorescence appearance and mean SD-OCT height of HPS in GA were analyzed. Results: A total of 36 eyes of 25 patients ...

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    9. Potential new diagnostic tool for Alzheimer's disease using a linear discriminant function for Fourier domain optical coherence tomography

      Potential new diagnostic tool for Alzheimer's disease using a linear discriminant function for Fourier domain optical coherence tomography

      Purpose: To calculate and validate a linear discriminant function (LDF) for Fourier domain optical coherence tomography (OCT) to improve the diagnostic ability of retinal and retinal nerve fiber layer (RNFL) thickness parameters in the detection of Alzheimer's disease (AD). Method: AD patients (n=151) and age-matched, healthy subjects (n=61) were enrolled. The Cirrus and Spectralis OCT systems were used to obtain retinal measurements and circumpapillary RNFL thickness for each participant. A LDF was calculated using all retinal and RNFL OCT measurements. Receiver operating characteristic (ROC) curves were plotted and compared among the LDF and the standard parameters provided ...

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    10. Vitreous Hyper-Reflective Dots in Optical Coherence Tomography and Cystoid Macular Edema after Uneventful Phacoemulsification Surgery

      Vitreous Hyper-Reflective Dots in Optical Coherence Tomography and Cystoid Macular Edema after Uneventful Phacoemulsification Surgery

      Purpose To report the observation of hyper-reflective dots in the vitreous cavity using spectral domain optical coherence tomography (SD-OCT) after uneventful phacoemulsification cataract surgery and to investigate their association with cystoid macular edema (CME). Materials and Methods Medical records of consecutive Asian patients who had no preoperative retinopathy and underwent uneventful phacoemulsification cataract surgery from March 2012 through February 2013 were reviewed. SD-OCTs were performed before, 1 week, and 1 month after surgery. The number of vitreous hyper-reflective dots (VHDs) was counted in 5 OCT images of high-definition 5-line raster scans. The development of CME was assessed using postoperative 1-month ...

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    11. High Power Laser Sources At Exotic Wavelengths

      High Power Laser Sources At Exotic Wavelengths

      High power laser sources at exotic wavelengths may be a step closer as researchers in China report a fibre optic parametric oscillator with record breaking efficiency. The research team believe this could lead to new light sources for a range of biomedical imaging applications. Mature commercial laser platforms are available for common output wavelengths. Some applications, however, require wavelengths that cannot readily be produced with established technologies. Several of these are in the field of biomedical imaging and spectroscopy (e.g. coherent anti-Stokes Raman scattering microscopy and optical coherence tomography). In such systems if the wavelength of light used can ...

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    12. Advancing OCT Algorithmic Standardization

      Advancing OCT Algorithmic Standardization

      Neovascular exudative AMD (wet AMD) continues to rank as a top reason to visit eye care specialists, and the early identification of this disease has important prognostic implications for patients. 1 Advancements in optical coherence tomography (OCT) imaging have surpassed other modalities in the ability to detect the earliest development of wet AMD and prompt treatment initiation, in spite of lack of inter- and intradevice standardization. 2 , 3 Zhang et al. 4 present a novel, automated way to detect changes at the border where choroidal neovascularization (CNV) first affects the retina. They use a technique that presents an automated method ...

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    13. Phase correction using programmable phase modulator (PPM) in optical coherence tomography

      Phase correction using programmable phase modulator (PPM) in optical coherence tomography

      Purpose Adaptive optics is used in optical coherence tomography (OCT) in order to improve lateral resolution based on aberration correction. Methods Experiments were performed to compensate higher order aberrations based on wavefront sensing and correction scheme using adaptive optics. The device utilized for compensation is parallel-aligned nematic liquid crystal spatial light modulator (PAL-SLM), PPM X7550 series. Wavefront of light at the sample path was measured by using OCT for aberration correction. Since the phase information can be obtained from interferogram therefore no additional optics is used. The performance of this device is evaluated for the correction of linear tilt aberration ...

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    14. Full-range Fourier domain Doppler optical coherence tomography based on sinusoidal phase modulation

      Full-range Fourier domain Doppler optical coherence tomography based on sinusoidal phase modulation

      A novel full-range Fourier domain Doppler optical coherence tomography (full-range FD-DOCT) using sinusoidal phase modulation for B-M scan is proposed. In this sinusoidal B-M scan, zero optical path difference (OPD) position does not move corresponding to lateral scanning points in contrast to linear B-M scan. Since high phase sensitivity arises around the zero OPD position, the proposed full-range FD-DOCT can achieve easily high velocity sensitivity without mirror image around the zero OPD position. Velocity sensitivity dependent on the OPD and the interval of scanning points is examined, and flow velocity detection capability is verified through Doppler imaging of a flow ...

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    15. Optical coherence tomography characteristics of the iris in Cogan-Reese syndrome

      Optical coherence tomography characteristics of the iris in Cogan-Reese syndrome

      PurposeTo describe the characteristic optical coherence tomography (OCT) findings of the iris in Cogan-Reese syndrome.MethodsA 63-year-old woman was referred for consultation due to diffuse pigmentation of the iris and elevated intraocular pressure (IOP) in the left eye. The clinical examination revealed Cogan-Reese syndrome with pedunculated iris outcroppings on the entire iris surface, and no peripheral anterior synechia. The right eye was normal with normal IOP.ResultsImaging the left iris with the CAM-L cornea lens adapter of the Optovue Fourier-domain OCT (RTVue-OCT) showed a folded iris surface, an increased total iris thickness, and an increased distance between the anterior and ...

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    16. See all articles
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  6. Picture Gallery

    Two Postdoctoral Positions in Optical imaging at Casey Eye Institute, Oregon Health & Science University, Portland, OR, USA Swept-source OCT and glaucoma Intra-operative OCT devices for ophthalmic use: an overview Measurement of wavefront aberrations and lens deformation in the accommodated eye with optical coherence tomography-equipped wavefront system Virtual reality simulator for vitreoretinal surgery using integrated OCT data Assessment of early occlusal caries pre- and post- sealant application—An imaging approach Optical frequency domain imaging in patients with Barrett's neoplasia: an ex vivo case study with correlated endoscopic and histology views Postdoctoral Associate Position in Biophotonics at Stanford University Expanding OCT: Quanitifying the Cornea’s Optical Performance Postdoctoral Research Fellowships in Optical Coherence Tomography at Wellman Center for Photomedicine Massachusetts General Hospital Adaptive replanning intensity-modulated radiotherapy for choroidal metastasis of breast cancer using optical coherence tomography St. Jude Medical Recognized as Innovative Technology Supplier of the Year by Nation’s Largest Health Care Contracting Organization
  7. Recent Quotes

    1. The newest swept-source OCT has the advantage that the light source frequency sweep range and repetition rate can be adjusted to tailor the resolution, imaging range, and axial scan repetition rate for the specific imaging application.
      By James G. Fujimoto
    2. The light source emits different frequencies sequentially and is acquired at a very rapid speed. Also, the average wavelength is longer than SD-OCT. The premise is that you get deeper penetration into the tissue without the shadowing artifacts from overlying blood vessels like you do with SD-OCT.
      By Lucy Q. Shen
    3. This latest innovation from Bioptigen enables faster alignment, targeted explorations, and brilliant visualizations, while simultaneously viewing both OCT and color fundus images in real time...We expect this capability will be impactful not only for mouse and rat research, but also for handheld, dual-modality imaging of larger animals including cats, dogs, rabbits, and non-human primates," Buckland added. Bioptigen has begun producing and shipping the new multimodality systems from the company's North Carolina operations center, and will showcase the product at ARVO 2014 in Orlando, May 4-8.
      By Eric L. Buckland
    4. Currently available imaging equipment such as computer tomography or magnetic resonance tomography does not help us to analyse processes at the cell level like vascular deposits
      By Georg Rose
    5. It was a difficult decision but after numerous attempts by many dedicated people our ability to turn Imalux into an on-gong business was just not going to happen. The decision to cease operations is closely related to the significant financing challenges faced by early stage medical device companies in general and imaging companies specifically. It is unfortunate we closed the business but both current and past members of our team can be proud of all that was accomplished in trying to bring a new imaging technology to market. At some point there is little doubt our pioneering technology will be clinically adopted on a large scale in medicine. We thank our customers, investors and partners for their support and assistance over the years.
      By James M. Fulton
    6. We are pleased to have this clearance, and confident the results reflect the quality of our diagnostic tools in imaging that assist doctors in diagnosing ocular diseases
      By Motoki Ozawa
    7. Miniaturization of OCT-based imaging technology on integrated photonics enables a novel, unique generation of not only cost-effective, but also compact, robust and nearly maintenance-free handheld OCT systems...The partners of the BiopsyPen Project have exquisite complementary expertise to accomplish a significant step towards this ambitious goal.”
      By Wolfgang Drexler
    8. This unique collaboration of leading European technology and clinical centers will allow us to significantly extend the technical possibilities and clinical indications of our micro-chip based OCT system
      By Eduardo Margallo Balbás
    9. The positive results from our study clearly demonstrate the clinical benefits of using our VivoSight OCT system in the diagnosis and monitoring of basal cell carcinoma. We believe that VivoSight has the potential to become the standard of care for the non-invasive diagnosis and monitoring of certain diseases and conditions that affect the skin, and in particular non-melanoma skin cancers. We look forward to releasing the full data in due course.
      By Jon Holmes
    10. The NvisionVLE Imaging System is an exciting new imaging technology that is enabling physicians to visualize esophageal abnormalities at and below the mucosal surface, helping inform clinical decision-making... “With new hospitals adopting the technology every month, and with the support of our investors and strategic guidance of our board, we can continue to expand our sales force to facilitate the adoption of NvisionVLE at more centers. Hospitals from New England, to Florida, to California are already offering this advanced imaging technology. We will continue to build out our operational capacity to meet the increasing demand for our products, while also working on new features and product offerings for the future.
      By Charles Carignan